Directive antenna system



Jan. 6; 1942. R. BOERNER DIRECTIVE ANTENNA SYSTEM Filed Sept. 24, 1940 Bllll llll I .II II Al I I I I K 3---- :l 4 I I lllll I I INVENTOR.#0004, 3 5/?67? ATTOR Patented Jan. 6, 1942 2,269,075 ,7 ANTENNA SYSTEMRudolf Boerner, Berlin, Germany, ass ignor "to C. 1 LorenzAktiengesellschaft, Berlin, Germany, a

company I 1 Application September 24, 1949, Serial No. 358,065 InGermany-October 12,1939

For the directional intercommunication by high frequency radiationantenna combinations are necessary whose radiation characteristics arestrongest within a certain angle which should be small as far aspossible, whereas in all the other angles the directive characteristicshould be zero. However, disturbing secondary maxima arise in additionto that maximum value. The number of such secondary maxima is thegreater the larger the number of radiators constituting the respectiveantenna combination.

Methods are known by which such disturbing secondary radiations may beavoided. For instance, radiators may be arranged beside each other or ina plane in such a manner that their mutual distances are larger than M2,i being the wavelength, and further, that they are fed in accordancewith a binomial coefficient law.

By this means the zero values are increased in.

number and the secondary maxima attenuated. The amplitudes of-these,however, do .not disappear completely. Such arrangement comprisesreflecting dipoles located in the same height as the main dipoles. I.

In another prior arrangement the radiators are fed with cophasalcurrents which decrease in intensity in the direction from themid-antenna toward the outer antennae. In this case the number andstrength of the secondary maxima may be diminished by making the mutualdistances of the antennae smaller than M It has been found that thesecondary maxima which arise with an antenna combination can be avoidedwith the aid of a suitable auxiliary radiation. For this purpose anadditional antenna combination or several such combinations are arrangedto act as reflecting antenna systems which if fed at the proper phase,as by radiation, for instance, add to the efficiency of the antennacombination.

The invention described hereafter relates to arrangements of the lattertype.

In the drawing, Figs. 1 to 8 are diagrams showing each an embodiment ofthe invention.

Arrangements as provided by the invention comprise a linear antennasystem, that is, a rectilinear row of radiators A, and an auxiliaryantenna system composed of radiators B. In the case of Figs. 1 and 2 theradiators B are pro.

vided on both sides of the row of radiators A,

whereas Figs. 3 and 4 show them arranged on only. one side thereof, theother side being occupied by a plane reflector C, as earth, for in--stance. The radiators B are not located beside the radiators A but areoffset with respect to these, thus being arranged in positions thatcorrespond to the gaps between the radiators A. Furthermore, theradiators B are preferably arranged in groups on the circumference ofcircles which have the radiators A as centre point and whose radius is1'=0.27 and they are likewise arranged to form a rectilinear row.

Antenna combinations of this construction have a directional effect offairly constant sharpness and act greatly to suppress the secondarymaxima of the radiation characteristics produced by the usual systemscomprising radiators disposed in a rectilinear row, and hence can beemployed wherever these systems are used, even if these are unsuitableon account of unduly high secondary maxima arising in them.

A good efilciency, better than that of the ordinary systems by values upto 20%, is obtained Also, systems as provided by the invention may belocated above each other so as to compose a structure of the 'kindrepresented in Figs. 5 or 6. This structure comprises dipoles arrangedin planes and produces in the two planes of polarization a directivebeam free from secondary maxima. One of the reflecting dipole planes maybe replaced by an arrangement having a reflecting surface spaced fromthe midplane by a distance which preferably equals 0.2 to 0.27)., aunilateral directive characteristic free from secondary radiation beingobtained in this way.

Furthermore, as shown in Figs. 7 and 8, in the case of a symmetricarrangement a reflect- 40 mg surface D, such as earth, may be located intheplane of symmetry thereof, part of the antenna arrangement thus beingreplaced by its mirror reflection. The arrangement so obtained islikewise free from secondary radiation and may be useful in connectionwith broadcast an radiators, and the auxiliary radiators beingassociated in separate groups with respective ones of the mainradiators, the radiators of such groups each being arranged on thecircumference of circles having the associated main radiator as a centrepoint said auxiliary radiators being arranged out of alignment with aline through the associated main radiator normal to said rectilinearrows.

2. An antenna system according to claim 1, wherein the radius of saidcircles is equal to 0.2m, X being the wavelength.

3. An antenna system comprising a first rectilinear row of mainradiators, a second rectilinear row of auxiliary radiators, this secondrow being arranged on one side of the row of main radia tors, and meansdefining a reflecting surface located on the other side of said firstrow, the auxiliary radiators being associated in groups of at least twowith individual main radiators, such groups each being arranged on thecircumference of circles having its associated main radiator as a centrepoint.

4. An antenna system having a rectilinear row of main radiators and arectilinear row of auxiliary radiators which extends along a lineparallel to the row of main radiators, the auxiliary radiators beingassociated in separate groups with respective ones of the mainradiators, each such group comprising two of the auxiliary radiatorsthese two radiators forming with their associated main radiator asvertex angle of 90

